A conventional locomotive is generally supported on rails by an arrangement of suspension elements or bogies. While various arrangements are available, a typical locomotive is supported by two bogies, each having a plurality of wheelsets. In one known configuration, each bogie supports three wheelsets where each wheelset includes two wheels that are joined by an axle. The typical bogie also supports propulsion or drive mechanisms, such as an electric motor, to drive the wheelsets. Often, due to certain economic advantages, only one or two of the wheelsets of a bogie are driven by electric motors, while the remaining wheelsets support a portion of the load but are otherwise left to idle. While such configurations can provide economic benefits, these configurations also introduce concerns that have yet to be resolved.
While achieving optimal traction is a common concern for all locomotives, traction is a particular concern in locomotives using the bogie arrangements noted above, where only two out of three wheelsets are driven. In general, traction can be improved by increasing axle load on the driven wheels. However, regulatory requirements and other constraints place an upper limit on the amount of axle load that is allowed for a set of rails. Although it may be possible to overcome some of these limitations using active suspension solutions, currently available solutions tend to be impractical and/or inadequate.
One active solution is disclosed in U.S. Pat. No. 8,313,111 (“Ahuja”), which discloses a suspension system for locomotives with three wheelsets per bogie. In particular, the system in Ahuja shifts more weight onto the endmost wheelsets of each bogie by raising the center wheelset off of the rails. Although the solution may be effective in transferring weight to the drive wheels, Ahuja's configuration involves a complete redesign of the suspension and other substantial modifications to the conventional bogie. Moreover, Ahuja's solution may be costly to implement and not readily retrofittable to existing bogies and suspension components. Furthermore, Ahuja is only applicable to bogie configurations that have center-mounted idler wheelsets and endmost driven wheelsets, which are relatively less common among conventional bogie arrangements.
In view of the foregoing disadvantages associated with conventional locomotives, a need exists for a solution that is not only applicable to more commonly used bogie configurations, but also simple and cost-efficient enough to implement or retrofit. There is also a need for a system that can substantially improve traction or adhesion without exceeding regulatory constraints and without adversely affecting the overall performance of the locomotive. Furthermore, there is a need for an active system that can actively adjust axle load and traction according to changing operating conditions. The present disclosure is directed at addressing one or more of the deficiencies and disadvantages set forth above. However, it should be appreciated that the solution of any particular problem is not a limitation on the scope of this disclosure or of the attached claims except to the extent expressly noted.